A system performs a layout design of a circuit for a small area satisfying a design rule within a short period of time. In a layout design system which includes a processing portion and in which a circuit diagram and layout design information are input to the processing portion, the processing portion has a function of generating layout data from the circuit diagram and the layout design information by performing a Q learning, the processing portion has a function of outputting the layout data, the processing portion includes a first neural network, and the first neural network estimates an action value function in the Q learning.